This invention relates generally to surgical evacuators for withdrawing fluid from the human body, and more particularly to a manually-operated evacuator of exceptionally simple and efficient design.
In post-operative surgical procedures, drains are used whenever an abnormal collection of fluid is encountered, be it contaminated or infected material, blood, bile or lymph, exudate or transudate. Ordinary wounds are normally drained for a post-operative period running as long as forty-eight hours. Effective drainage is of medical importance, for swelling and tension are minimized thereby, post-operative pain is reduced, and wound edges are maintained flat and quiescent.
In order to do away with costly electrical and mechanical drainage pumps, it is known to use a manually-operated evacuator, such as the type disclosed in U.S. Pat. No. 3,115,138. This evacuator is constituted by a collapsible, fluid-tight, flexible container having rigid top and bottom plates therein which are engaged by helical springs acting to separate the plates. When the plates are pressed together to collapse the container, the springs therebetween are compressed to reduce the volume of the container, thereby exhausting the atmosphere from the container through an open discharge outlet. When the outlet is closed and the plates are thereafter released, the springs act to return the collapsed container to its original shape. The resultant partial vacuum produces a suction force which acts to draw fluid from an operative wound through a drain tube coupled to the container.
While such manually-operated evacuators are less costly than electrical and mechanical pumps, they nevertheless have a relatively complex structure and are fairly difficult and expensive to manufacture. Moreover, since evacuators of this type are discarded after use on a patient, the cost of the evacuator may become a major hospital expense, for hundreds of such evacuators are used in a typical city hospital in the course of a year.
Also, in a conventional, manually-operated evacuator, the drain tube inlet and the discharge outlet are mounted on the top wall of the collapsible container which includes the rigid top plate. The reason for this is that the flexible side wall of the container is collapsed when the container is compressed. It is not feasible, therefore, to place the inlet and outlet in the side wall, for the tube and plug associated therewith may be dislodged when the container is compressed.
On the other hand, with the inlet and outlet mounted on the top wall of the container, one must be careful, when pressing the wall down to evacuate the atmosphere, not to dislodge the associated tube and plug, as this makes it inconvenient to apply adequate manual pressure to the container to fully exhaust the atmosphere therein. The amount of negative pressure depends, of course, on the extent to which the container is collapsed, and should only a partial collapse be effected, the resultant negative pressure may be inadequate to carry out effective drainage.